Mitochondrial Complex III Deficiency, Nuclear Type 1

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WHO-ICD-10 version:2010

Endocrine, nutritional and metabolic diseases

Metabolic disorders

OMIM Number

124000

Mode of Inheritance

Autosomal recessive

Gene Map Locus

2q35

Description

Mitochondrial complex III deficiency is a severe multisystem disorder with onset at birth, characterized with lactic acidosis, hypotonia, hypoglycemia, failure to thrive, encephalopathy, and delayed psychomotor development.  Visceral involvement may also occur, including hepatopathy and renal tubulopathy. 

The prevalence of the condition is unknown, although the disease is thought to be rare.  Many patients die in early childhood, but individuals with mild signs and symptoms can survive into adolescence or adulthood.

Mitochondrial complex III deficiency is inherited as autosomal recessive.  This disease exhibits considerable genetic heterogeneity, and can be caused by different mutations in the BCS1L gene (2q35) encoding a protein essential for the assembly of complex III in the mitochondrial respiratory chain.

Epidemiology in the Arab World

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Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
603358.1United Arab EmiratesFemaleNoYes Intrauterine growth retardation; Failure...NM_001079866.1:c.385G>AHomozygousAutosomal, RecessiveSaleh et al. 2021 Authors not sure wht...

Other Reports

Saudi Arabia

Al-Owain et al (2013) described nine Saudi patients affected with lactic acidosis from four consanguineous families; three of them were related.  Novel behavioral and psychiatric phenotypes were observed in some of the patients associated with the p.Gly129Arg BCS1L gene mutation.  This causative mutation in the BCS1L gene was identified in all affected members using linkage, homozygosity mapping and targeting sequencing.  The psychiatric symptoms started after childhood as hypomania, later it evolved into intermittent pyschosis.  Patient one was a 14 year-old boy who presented with bilateral horizontal nystagmus, moderate sensorineural hearing loss, impairment of dexterity abilities and visual spatial skills.  His IQ was 80, and he had mild ADHD.  He had notable sense of humor with sarcasm, talkativeness, hyperactivity, insomnia, obsessional intrusive thoughts and preferred isolation.  At the age of 21 he developed auditory and visual hallucination associated with paranoid delusion and depressed symptoms.  He had three siblings with lactic acidosis (patients 2, 3, and 4).  Also family two (patients 5 and 6) and three (patient 7) were related to him.  Patient eight was a Saudi boy who had hypoglycemia and severe metabolic acidosis on the first day of life.  He had problems in organization, pure problem solving and social skills.  His IQ was 63 at the age of 15 years.  He also had horizontal nystagmus with visual acuity of 20/200.  He had talkativeness, verbal disinhibition, yelling, and hypomania.  He was also detached, stubborn, and unsociable.  At the age of 26 years he developed severe rhabdomylosis and acute renal failure.  He was on vegetative state due to recurrent episodes of metabolic acidosis and encephalopathy.  He had a 13 year old brother (patient 9) with early onset lactic acidosis, and two siblings (a boy and a girl) who died with suspected lactic acidosis. 

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